Aquarium hobbyists have tried many techniques for feeding aquatic animals during periods of absence. The primary approach has been a series of devices which contain a supply of food from which the fish eat at will. The food is not automatically dispensed from these devices into the aquarium and, because of differing dietary habits, the fish may or may not take the food from such an apparatus. Using this type of device is particularly unsuccessful with fish that prefer to eat food after it has settled on the floor of the aquarium.
A second and somewhat more satisfactory approach is disclosed in U.S. Pat. Nos. 2,900,022 to Friedman and 2,905,144 to Prigg. Both of these devices utilize the theory of liquid evaporation as a motivating force to empty food from a container into an aquarium. The patent to Prigg discloses an apparatus which floats on top of the water inside the aquarium and, as normal evaporation of the aquarium water occurs, a series of trays are successively activated at periodic intervals to deposit food into the water. Other than size and difference in operation, one disadvantage to this apparatus is the necessity of floating a part of the apparatus in the aquarium. Water disturbances caused by fish jumping or the malfunction of a filtering system which could alter the rate of evaporation, could cause the float to activate the feed trays at erratic intervals.
The patent to Friedman is a device which includes an activating arm tilted by liquid evaporation from a container attached to the arm. As the liquid evaporates a counterweight causes the arm to rotate slowly into contact with each of a series of tripping arms which are attached individually to feed trays that tilt to pour food into the aquarium. This apparatus is somewhat efficient as long as each mechanism works properly. However, misalignment of the activating arm would cause a malfunction; also should a trip arm malfunction, the activating arm may become stuck at any position and prevent further distribution of food into the aquarium. Because of the number of cooperating elements in the Friedman apparatus, there is considerable likelihood of malfunction while no one is available to correct the problem.